• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.9
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• pp.707-713
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• 2006

To improve heating performance of the heat pump in winter season, refrigerant heating device was applied to conventional heat pump. The refrigerant heating device operates at the heating capacity does not enough to the heating load requirement of the conditioning space. When the discharge air temperature of the indoor heat exchanger goes down to below $40^{\circ}C$ which is criterion for comfort of the occupants in the conditioning space, the system also starts. The refrigerant heating system has new concept of auxiliary heating device for heat pump in winter. In this study, the system performance was analyzed through experiments and parametric study was conducted to improve the COP and control strategies.

• Tribology and Lubricants
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• v.35 no.4
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• pp.206-214
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• 2019

This study investigates alternative refrigerants and refrigerant oils as well as the tendency of protecting the global environment in view of automobile air-conditioning systems. Since decades, the R12 refrigerant is not used in automobile air-conditioners because of the ozone depletion potential (ODP) problem, and for the last 20 years, the ODP-free R134a refrigerant is leading the new automotive air-conditioning market. However, owing to its high global warming potential (GWP), the R134a refrigerant use in automobile air-conditioning system is also prohibited by law, and alternative refrigerants with a low GWP need to be proposed. Therefore, recently, the application of R1234yf, R152a, or other alternative refrigerants has started worldwide. By contrast, natural refrigerant R744 was introduced in the market several years ago by VDA (Verband Der Automobilindustrie), which is a German association in the automotive industry. This study also deals with refrigerant oils. For a long time, polyalkylene glycol (PAG) oil has been traditionally used with automobile air-conditioners, and polyolester (POE) oil is suitable for HEV, PHEV, and EV air-conditioning systems, where it is used by the electrically driven compressor owing to its excellent electrical insulation properties. Finally, PAG is an excellent lubricant for all the R134a, R152a, R1234yf, and R744 refrigerants, and has the advantage that it can be applied rapidly to alternative refrigerant air-conditioning systems.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.3
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• pp.181-190
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• 1988

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.23 no.6
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• pp.510-515
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• 1994

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.32 no.8
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• pp.46-52
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• 2003

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.27 no.1
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• pp.14-27
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• 1998

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.27 no.1
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• pp.37-52
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• 1998

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.23 no.3
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• pp.191-203
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• 1994

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.23 no.3
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• pp.236-246
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• 1994

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.23 no.3
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• pp.247-252
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• 1994